Carrier Test Page

Ataxia-Telangiectasia

What is Ataxia-Telangiectasia?

Ataxia-Telangiectasia (AT) is an inherited disorder that affects the nervous system, immune system, and other systems in the body. People with AT develop progressive difficulty with coordinating movements in early childhood. Other movement and neurological problems may develop, and the affected children may be wheelchair bound by adolescence. One of the characteristics of this condition is called telangiectases, which are small clusters of enlarged blood vessels in the eyes or on the surface of the skin. Individuals with AT often have a weak immune system and a high risk to develop cancers. The life expectancy of people with AT may be shortened, but most can live into adulthood. Intellectual disability or learning problems are not associated with AT. AT is caused by pathogenic variants in the ATM gene.

How is Ataxia-Telangiectasia inherited?

AT is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

Although individuals who carry one copy of the defective ATM gene do not have AT, they are at increased risk of developing cancers and heart disease. Additionally, their risk to have a child affected with AT is increased. Genetic counseling and testing of reproductive partners is recommended for carriers of AT.